We shall be continuing to examine intact plant tissues in terms of their capacity to convert oleic acid to linoleic and thence to linolenic acid. A number of variables such as light duration, dark duration, temperature changes will be examined. The kinetics of sequential desaturation will be examined in other tissues to establish a unified concept. With the purified stearoyl ACP desaturase, kinetics, oxygen activation, the nature of the redox-pigment system will be examined in detail.